OBJECTIVE: Elevated circulating levels of IL-18 can predict future coronary heart disease. Although IL-18 is thought to play a crucial role in atherosclerosis, whether circulating IL-18 levels are associated with the severity of atherosclerosis remains to be determined. With the use of B-mode ultrasound, this study examines the relationships of serum IL-18 levels with carotid intima-media thickness (IMT) as a reflector for systemic atherosclerosis.
METHODS AND RESULTS: The study comprised 366 patients without histories of cardiovascular accidents. Severity of carotid atherosclerosis was evaluated by the mean max IMT, ie, mean of the maximal wall thickness at 12 carotid segments. Serum IL-18, IL-6, and high-sensitive C-reactive protein (hs-CRP) levels were determined in all patients. Log-transformed IL-18 concentrations were positively correlated with IMT (r=0.36, P<0.001), and the association remained significant (beta=0.20, P<0.001) when controlling for traditional atherosclerotic risk factors, IL-6 and hs-CRP levels. Also, IMT was greater in the highest and the middle tertile of IL-18 levels than in the lowest tertile.
CONCLUSIONS: Higher serum IL-18 levels appear to be associated with greater carotid IMT, suggesting the link between IL-18 and atherosclerosis.